When a man shall have in the skin of his flesh a rising, a scab, or bright spot, and it be in the skin of his flesh like the plague of leprosy; then he shall be brought unto Aaron the priest, or unto one of his sons the priests: The plague of leprosy - This dreadful disorder has its name leprosy, from the Greek λεποα, from λεπις, a scale, because in this disease the body was often covered with thin white scales, so as to give it the appearance of snow. Hence it is said of the hand of Moses, Exodus 4:6, that it was leprous as snow; and of Miriam, Numbers 12:10, that she became leprous, as white as snow; and of Gehazi, 2 Kings 5:27, that, being judicially struck with the disease of Naaman, he went out from Elisha's presence a leper as white as snow. See Clarke's note on Exodus 4:6. In Hebrew this disease is termed צרעת tsaraath, from צרע mor tsara, to smite or strike; but the root in Arabic signifies to cast down or prostrate, and in Ethiopian, to cause to cease, because, says Stockius, "it prostrates the strength of man, and obliges him to cease from all work and labor." There were three signs by which the leprosy was known.
1. A bright spot.
2. A rising (enamelling) of the surface.
3. A scab; the enamelled place producing a variety of layers, or stratum super stratum, of these scales.
The account given by Mr. Maundrell of the appearance of several persons whom he saw infected with this disorder in Palestine, will serve to show, in the clearest light, its horrible nature and tendency. "When I was in the Holy Land," says he, in his letter to the Rev. Mr. Osborn, Fellow of Exeter College, "I saw several that labored under Gehazi's distemper; particularly at Sichem, (now Naplosu), there were no less than ten that came begging to us at one time. Their manner is to come with small buckets in their hands, to receive the alms of the charitable; their touch being still held infectious, or at least unclean. The distemper, as I saw it on them, was quite different from what I have seen it in England; for it not only defiles the whole surface of the body with a foul scurf, but also deforms the joints of the body, particularly those of the wrists and ankles, making them swell with a gouty scrofulous substance, very loathsome to look on. I thought their legs like those of old battered horses, such as are often seen in drays in England. The whole distemper, indeed, as it there appeared, was so noisome, that it might well pass for the utmost corruption of the human body on this side the grave. And certainly the inspired penman could not have found out a fitter emblem, whereby to express the uncleanness and odiousness of vice." - Maundrell's Travels. Letters at the end. The reader will do well to collate this account with that given from Dr. Mead; see the note on Exodus 4:6 (note).